SYSTEM INTEGRATION MODULE
M68HC16 Z SERIES
5-22
USER’S MANUAL
NOTE
The internal oscillator which supplies the input frequency for the PLL
always runs when a crystal is used.
Figure 5-6 SIM LPSTOP Flowchart
USING
EXTERNAL CLOCK?
NO
YES
USE SYSTEM CLOCK
AS SIMCLK IN LPSTOP?
NO
YES
SET STSIM = 1
f
simclk
1
= f
sys
IN LPSTOP
WANT CLKOUT
ON IN LPSTOP?
NO
YES
NO
YES
WANT CLKOUT
ON IN LPSTOP?
SET STSIM = 0
f
simclk
1
= f
ref
IN LPSTOP
SET STEXT = 1
f
clkout
2
= f
sys
f
eclk
=
÷
f
sys
IN LPSTOP
SET STEXT = 0
f
clkout
2
= 0 Hz
f
eclk
= 0 Hz
IN LPSTOP
SET STEXT = 1
f
clkout
2
= f
ref
f
eclk
= 0 Hz
IN LPSTOP
SET STEXT = 0
f
clkout
2
= 0 Hz
f
eclk
= 0 Hz
IN LPSTOP
ENTER LPSTOP
NOTES:
1. THE SIMCLK IS USED BY THE PIT, IRQ, AND INPUT BLOCKS OF THE SIM.
2. CLKOUT CONTROL DURING LPSTOP IS OVERRIDDEN BY THE EXOFF BIT IN SIMCR. IF EXOFF = 1, THE CLKOUT
PIN IS ALWAYS IN A HIGH-IMPEDANCE STATE AND STEXT HAS NO EFFECT IN LPSTOP. IF EXOFF = 0, CLKOUT
IS CONTROLLED BY STEXT IN LPSTOP.
SET UP INTERRUPT
TO WAKE UP MCU
FROM LPSTOP
SIM LPSTOPFLOW
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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